All you need is one microscopic DNA-containing cell with a long tail swimming madly to meet up with an egg. How difficult can it be? Plenty, according to Etta Bradecamp, DVM, who puts the odds at about one in a billion for a pregnancy arising from just one sperm and one egg. Bradecamp, a practitioner with Rood & Riddle Equine Hospital, in Lexington, Ky., described the challenges of processing semen for shipping at the 2011 American Association of Equine Practitioners convention, held Nov. 18-22 in San Antonio, Texas.

"The use of cooled-shipped semen to inseminate mares is widespread in the industry, and not all spermatozoa tolerate cooling," she explained. "In addition, not all ejaculates, even from a ‘proven’ stallion, are the same and need to be constantly evaluated to ensure that no less than one billion sperm cells capable of progressive motion are shipped in each order."

In addition to the challenges associated with cooling and shipping the sperm and inseminating the mare, some stallions simply do not produce a high-quality ejaculate in the first place. "Stallions are often selected based on attributes such as physique or athleticism, not their sperm quality," said Bradecamp.

Thus, when faced with a stallion that produces a low-quality ejaculate, meaning it contains low numbers of spermatozoa that do not move well or do not tolerate cooling, it’s important to take special steps to maximize the chances of impregnating the recipient mare.

Among these steps are the following:

  • Handle the sperm carefully after collection to avoid "shock" (i.e.,